docs: def setPhysicalMaximum(self, edfsignal, physical_maximum):
          """
          Sets the physical_maximum of signal edfsignal.
  
          Parameters
          ----------
          edfsignal: int
              signal number
          physical_maximum: float
              Sets the physical maximum
  
          Notes
          -----
          This function is required for every signal and can be called only after opening a file in writemode and before the first sample write action.
          """
          if edfsignal < 0 or edfsignal > self.n_channels:
              raise ChannelDoesNotExist(edfsignal)
          self.channels[edfsignal]['physical_max'] = physical_maximum
          self.update_header()